PURPOSE: To flexibly deform even the intermediate part of a cleaning blade for effectively scrapping up dust by providing a cut-out space extending from the tip to the proximal side in the intermediate part of respective cleaning blades and providing the cut-out spaces of the remaining cleaning blades axially shifted relative to one cut-out space.

CONSTITUTION: A rotary shaft 5 of a rotor 4 disposed in an intake port 2a is provided with a plurality of cleaning blades 6 of a movable material. A cut-out space 10 extending from the tip to the proximal part is provided in the intermediate part in the axial direction of each cleaning blade 6. A plurality of cut-out spaces 10 are all arranged in the axial the directing the rotary shaft 5 with a predetermined interval displaced so that they do not overlap on each other in the circumferential direction of the rotary shaft 5. The intermediate part of the cleaning blade 6 is flexibly deformed along a cleaning surface by the cut-out space 10 to effectively scrape up dust. Also, even if dust cannot be scraped up in the cut-out space 10 of are cleaning blade 6, dust is surely scraped up by the other cleaning blades 6.